1. Field of the Invention
The present invention relates to an apparatus for testing an integrated circuit (hereinafter referred to as “IC”), and more particularly to an apparatus for testing an IC which comprises both digital and analog circuit components.
2. Description of the Related Art
One conventional IC testing apparatus is shown in FIG. 7 of the accompanying drawings. As shown in FIG. 7, the conventional IC testing apparatus has a power supply 1, a controller 2, a time-based synchronizing system 3 for synchronizing various measuring components with a given timing signal, and a device interface 4 for connecting the measuring components to an IC device under test. The conventional IC testing apparatus also has, as its measuring components, a digital I/O device (often a plurality of digital I/O devices) 5 for exchanging digital signals with a digital signal terminal of the IC device under test to determine whether the IC device under test is acceptable or not, an audio-band AWG (Arbitrary Waveform Generator) 6 and a video-band AWG 7 for applying known signals to an analog signal input terminal of the IC device under test, and an audio-band digitizer 8 and a video-band digitizer 9 for detecting a signal from an analog signal output terminal of the device under test to determine whether the IC device under test is acceptable or not. The conventional IC testing apparatus may have a plurality of AWGs and a plurality of digitizers having different bands and different resolutions depending on the signal frequency that is handled and the required level of accuracy.
For testing an IC device, the conventional IC testing apparatus applies a predetermined signal to the IC device under test, and compares an output signal from the IC device under test with an expected value. For testing an IC which comprises both digital and analog circuit components, it is necessary to perform a digital output test using a digital comparator and an analog output test using an analog comparator.
Specifically, a digital test signal generated by a digital signal generator is applied to the IC under test, and an analog signal outputted from the IC under test is converted by an analog-to-digital converter into numerical data, which is stored in a capture memory. Thereafter, a processor processes the numerical data stored in the capture memory to calculate parameters necessary to evaluate analog output characteristics of the IC under test, and determines whether the IC under test is acceptable or not using the parameters. A digital signal outputted from the IC under test is compared with a value expected from an acceptable IC by a digital signal evaluation apparatus to determine whether the IC under test is acceptable or not.
According to the above conventional process, different testing units are used to test digital and analog output signals from an IC which comprises both digital and analog circuit components. Therefore, it is necessary to test such an IC with two testers, i.e., a digital IC tester and an analog IC tester, or a single large-scale IC tester comprising digital and analog test circuits.
Conventionally, the test system needs to have optimum test devices for handling respective attributes (e.g., digital and analog natures, frequency bands, resolutions, etc.) of a signal applied to or outputted from a device under test. Furthermore, testing a variety of devices requires a number of test devices having different performances to be available on hand.
In each test, the test device must be connected to corresponding terminals of the device under test. Such connections may need to be changed depending on the item to be measured. Changing connections makes the test time-consuming because it causes mechanical connectors such as relays to be turned on and off. Since terminal layouts of devices under test generally differ from device to device, it is necessary to prepare connecting jigs dedicated for the respective devices under test.
According to the recent trends of multifunctional ICs, there is a growing number of ICs in which a large-scale digital circuit and a simple analog circuit are integrated. Preparing a large-scale analog testing circuit for use with ICs comprising digital and analog circuit components makes the cost of testing ICs high.